Refactor graph classes

- Extract base graph logic from WeightedEdgeGraph into new Graph class
- Add LabelGraph to replace old Graph class used by LanParty solver
- Rename WeightedEdgeGraph to WeightGraph and change it to use new Graph class
- Update affected solvers to use new graph classes

include/aoc/LanParty.hpp

@@ -15,7 +15,7 @@
 
 #pragma once
 
-#include <aoc/common/Graph.hpp>
+#include <aoc/common/LabelGraph.hpp>
 #include <aoc/framework/Solver-types.hpp>
 
 class LanParty
@@ -27,9 +27,10 @@ class LanParty
     virtual void processDataLine(const std::string& line) override;
     virtual void finish() override;
 private:
-    Graph lan_;
+    static constexpr std::string getFirstTxComputerName();
-    void computeInterconnectedThreeSetCount(const Vertex& vertexTx);
+    static constexpr std::string getLastTxComputerName();
-    bool shallProcessVertex(const Vertex& vertexToCheck, const Vertex& vertexTx) const;
+    LabelGraph lan_;
-    const std::string getFirstTxComputerName() const;
+    int findOrAddVertex(const std::string& vertexId);
-    const std::string getLastTxComputerName() const;
+    void computeInterconnectedThreeSetCount(const int vertexTx);
+    bool canProcessVertex(const int vertexToCheck, const int vertexTx) const;
 };

include/aoc/RamRun.hpp

@@ -15,8 +15,9 @@
 
 #pragma once
 
+#include <aoc/common/GraphPathsResult.hpp>
 #include <aoc/common/Grid.hpp>
-#include <aoc/common/WeightedEdgeGraph.hpp>
+#include <aoc/common/WeightGraph.hpp>
 #include <aoc/framework/Solver-types.hpp>
 
 class RamRun
@@ -33,11 +34,11 @@ class RamRun
     int maxBytes_;
     int nBytes_;
     Grid<int> vertexReferences_;
-    WeightedEdgeGraph::PathsResult dijkstraResult_;
+    GraphPathsResult dijkstraResult_;
     static constexpr char getUnknownVertexReference();
     static constexpr char getNoVertexReference();
     bool tryMarkCorrupted(const std::string& line, int& corruptedVertex);
-    WeightedEdgeGraph buildGraph();
+    WeightGraph buildGraph();
-    int getVertex(WeightedEdgeGraph& graph, const size_t x, const size_t y);
+    int getVertex(WeightGraph& graph, const size_t x, const size_t y);
     void resetVertexReferences();
 };

include/aoc/ReindeerMaze.hpp

@@ -20,7 +20,7 @@
 #include <set>
 #include <vector>
 
-#include <aoc/common/WeightedEdgeGraph.hpp>
+#include <aoc/common/WeightGraph.hpp>
 #include <aoc/extra/ReindeerMazeCrossing.hpp>
 #include <aoc/extra/ReindeerMazePathIncidence.hpp>
 #include <aoc/framework/LinesSolver.hpp>
@@ -39,15 +39,15 @@ class ReindeerMaze
     static constexpr char getEndChar();
     static constexpr char getWallChar();
     static constexpr int getTurnCost();
-    void buildPathSegmentGraph(WeightedEdgeGraph& graph, VertexAttachedPositions& vertexAttachedPositions,
+    void buildPathSegmentGraph(WeightGraph& graph, VertexAttachedPositions& vertexAttachedPositions,
         const int entry, const int exit);
     void initializeWorkList(std::list<ReindeerMazeCrossing>& crossings, const int entryVertex);
     void addCheckedIncidence(std::vector<ReindeerMazePathIncidence>& incidences, const Point2 start,
         const Point2 direction);
-    void addPathSegmentEdges(WeightedEdgeGraph& graph, const ReindeerMazePathIncidence& pathIncidence,
+    void addPathSegmentEdges(WeightGraph& graph, const ReindeerMazePathIncidence& pathIncidence,
         const std::vector<ReindeerMazePathIncidence>& otherPathIncidences);
     std::pair<int, int> makePositionsIdPair(const Point2& position1, const Point2& position2);
-    int calcShortestPaths(const WeightedEdgeGraph& graph, const VertexAttachedPositions& vertexAttachedPositions,
+    int calcShortestPaths(const WeightGraph& graph, const VertexAttachedPositions& vertexAttachedPositions,
         const int entry, const int exit, const std::vector<int>& shortestDistances);
     int getNUniqueAttachedPositions(const VertexAttachedPositions& vertexAttachedPositions,
         const std::set<int>& vertices);

include/aoc/common/Graph.hpp

@@ -1,5 +1,5 @@
 // Solutions to the Advent Of Code 2024.
-// Copyright (C) 2024  Stefan Müller
+// Copyright (C) 2025  Stefan Müller
 //
 // This program is free software: you can redistribute it and/or modify it under
 // the terms of the GNU General Public License as published by the Free Software
@@ -15,18 +15,95 @@
 
 #pragma once
 
-#include <map>
+#include <iterator>
-#include <memory>
 #include <vector>
 
-#include <aoc/common/Vertex.hpp>
-
 class Graph
 {
 public:
-    const std::map<std::string, std::shared_ptr<Vertex>>& getVertices() const;
+    int addVertex();
-    void addEdge(const std::string& vertexId1, const std::string& vertexId2);
+    void addEdge(const int vertex1, const int vertex2);
+    size_t getNVertices() const;
+    size_t getNEdges() const;
+    bool areAdjacent(const int vertex1, const int vertex2) const;
+
+    struct Incidence
+    {
+    public:
+        Incidence(const int vertex, const int edge)
+            : vertex{ vertex }, edge{ edge }
+        {
+        }
+        int vertex;
+        int edge;
+    };
+
+    struct NeighborIterator
+    {
+    public:
+        // Iterator traits.
+        using difference_type = std::ptrdiff_t;
+        using value_type = Incidence;
+        using pointer = const value_type*;
+        using reference = const value_type&;
+        using iterator_category = std::forward_iterator_tag;
+
+        NeighborIterator(const Graph& graph, const int vertex)
+            : graph_{ graph }, incidence_{ -1 }, value_{ -1, -1 }
+        {
+            if (vertex >= 0 && vertex < graph_.firstVertexIncidences_.size())
+            {
+                setIncidence(graph_.firstVertexIncidences_[vertex]);
+            }
+        };
+        NeighborIterator& operator++()
+        {
+            if (incidence_ >= 0)
+            {
+                setIncidence(graph_.nextIncidences_[incidence_]);
+            }
+            return *this;
+        }
+        NeighborIterator operator++(int)
+        {
+            NeighborIterator it = *this;
+            ++(*this);
+            return it;
+        }
+        bool operator==(NeighborIterator other) const
+        {
+            return incidence_ == other.incidence_;
+        }
+        bool operator!=(NeighborIterator other) const
+        {
+            return !(*this == other);
+        }
+        const reference operator*() const
+        {
+            return value_;
+        }
+        const pointer operator->() const
+        {
+            return &value_;
+        }
+    private:
+        const Graph& graph_;
+        int incidence_;
+        value_type value_;
+        void setIncidence(const int incidence)
+        {
+            incidence_ = incidence;
+            if (incidence_ >= 0)
+            {
+                value_ = { graph_.incidenceVertices_[incidence_], incidence_ >> 1 };
+            }
+        }
+    };
+
+    NeighborIterator begin(const int vertex) const;
+    NeighborIterator end() const;
 private:
-    std::map<std::string, std::shared_ptr<Vertex>> vertices_;
+    std::vector<int> firstVertexIncidences_{};
-    std::shared_ptr<Vertex> findOrAddVertex(const std::string& vertexId);
+    std::vector<int> nextIncidences_{};
+    std::vector<int> incidenceVertices_{};
 };

include/aoc/common/GraphPathsResult.hpp

@@ -15,14 +15,19 @@
 
 #pragma once
 
-class VertexEdgeIncidence
+#include <vector>
+
+class GraphPathsResult
 {
 public:
-    VertexEdgeIncidence(const int vertex, const int next)
+    GraphPathsResult()
+        : distances{}, predecessors{}
     {
-        this->vertex = vertex;
-        this->next = next;
     }
-    int vertex;
+    GraphPathsResult(const size_t size, const int initialDistance, const int initialPredecessor)
-    int next;
+        : distances(size, initialDistance), predecessors(size, initialPredecessor)
+    {
+    }
+    std::vector<int> distances;
+    std::vector<int> predecessors;
 };

include/aoc/common/LabelGraph.hpp

@@ -0,0 +1,38 @@
+// Solutions to the Advent Of Code 2024.
+// Copyright (C) 2025  Stefan Müller
+//
+// This program is free software: you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <string>
+#include <map>
+#include <vector>
+
+#include <aoc/common/Graph.hpp>
+
+class LabelGraph
+{
+public:
+    int addVertex(const std::string& label);
+    void addEdge(const int vertex1, const int vertex2);
+    bool areAdjacent(const int vertex1, const int vertex2) const;
+    const std::string& getVertexLabel(const int vertex) const;
+    const std::map<std::string, int>& getLabelVertices() const;
+    Graph::NeighborIterator begin(const int vertex) const;
+    Graph::NeighborIterator end() const;
+private:
+    Graph graph_{};
+    std::vector<std::string> vertexLabels_{};
+    std::map<std::string, int> labelVertices_{};
+};

include/aoc/common/WeightGraph.hpp

@@ -0,0 +1,38 @@
+// Solutions to the Advent Of Code 2024.
+// Copyright (C) 2025  Stefan Müller
+//
+// This program is free software: you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <vector>
+
+#include <aoc/common/Graph.hpp>
+#include <aoc/common/GraphPathsResult.hpp>
+
+class WeightGraph
+{
+public:
+    static constexpr int getInfiniteDistance();
+    int addVertex(const int weight);
+    void addEdge(const int vertex1, const int vertex2, const int weight);
+    int getVertexWeight(const int vertex) const;
+    int getEdgeWeight(const int edge) const;
+    GraphPathsResult dijkstra(const int source) const;
+    Graph::NeighborIterator begin(const int vertex) const;
+    Graph::NeighborIterator end() const;
+private:
+    Graph graph_{};
+    std::vector<int> edgeWeights_{};
+    std::vector<int> vertexWeights_{};
+};

include/aoc/common/WeightedEdgeGraph.hpp

@@ -1,129 +0,0 @@
-// Solutions to the Advent Of Code 2024.
-// Copyright (C) 2025  Stefan Müller
-//
-// This program is free software: you can redistribute it and/or modify it under
-// the terms of the GNU General Public License as published by the Free Software
-// Foundation, either version 3 of the License, or (at your option) any later
-// version.
-//
-// This program is distributed in the hope that it will be useful, but WITHOUT
-// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
-// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along with
-// this program.  If not, see <http://www.gnu.org/licenses/>.
-
-#pragma once
-
-#include <iterator>
-#include <vector>
-
-#include <aoc/common/VertexEdgeIncidence.hpp>
-
-class WeightedEdgeGraph
-{
-public:
-    WeightedEdgeGraph();
-    int addVertex(const int weight = 0);
-    void addEdge(const int vertex1, const int vertex2, const int weight);
-    int getVertexWeight(const int vertex) const;
-    int getEdgeWeight(const int edge) const;
-
-    struct PathsResult
-    {
-        PathsResult()
-            : distances{}, predecessors{}
-        {
-        }
-        PathsResult(const size_t size, const int initialDistance, const int initialPredecessor)
-            : distances(size, initialDistance), predecessors(size, initialPredecessor)
-        {
-        }
-        std::vector<int> distances;
-        std::vector<int> predecessors;
-    };
-
-    PathsResult dijkstra(const int source) const;
-    static constexpr int getInfiniteDistance();
-
-    struct Incidence
-    {
-    public:
-        Incidence(const int vertex, const int edge)
-            : vertex{ vertex }, edge{ edge }
-        {
-        }
-        int vertex;
-        int edge;
-    };
-
-    struct NeighborIterator
-    {
-    public:
-        // Iterator traits.
-        using difference_type = std::ptrdiff_t;
-        using value_type = Incidence;
-        using pointer = const value_type*;
-        using reference = const value_type&;
-        using iterator_category = std::forward_iterator_tag;
-
-        NeighborIterator(const WeightedEdgeGraph& graph, const int vertex)
-            : graph_{ graph }, incidence_{ -1 }, value_{ -1, -1 }
-        {
-            if (vertex >= 0 && vertex < graph_.firstVertexIncidences_.size())
-            {
-                setIncidence(graph_.firstVertexIncidences_[vertex]);
-          }
-        };
-        NeighborIterator& operator++()
-        {
-            if (incidence_ >= 0)
-            {
-                setIncidence(graph_.vertexEdgeIncidences_[incidence_].next);
-            }
-            return *this;
-        }
-        NeighborIterator operator++(int)
-        {
-            NeighborIterator it = *this;
-            ++(*this);
-            return it;
-        }
-        bool operator==(NeighborIterator other) const
-        {
-            return incidence_ == other.incidence_;
-        }
-        bool operator!=(NeighborIterator other) const
-        {
-            return !(*this == other);
-        }
-        const reference operator*() const
-        {
-            return value_;
-        }
-        const pointer operator->() const
-        {
-            return &value_;
-        }
-    private:
-        const WeightedEdgeGraph& graph_;
-        int incidence_;
-        value_type value_;
-        void setIncidence(const int incidence)
-        {
-            incidence_ = incidence;
-            if (incidence_ >= 0)
-            {
-                value_ = { graph_.vertexEdgeIncidences_[incidence_].vertex, incidence_ >> 1 };
-            }
-        }
-    };
-
-    NeighborIterator begin(const int vertex) const;
-    NeighborIterator end() const;
-private:
-    std::vector<int> firstVertexIncidences_;
-    std::vector<VertexEdgeIncidence> vertexEdgeIncidences_;
-    std::vector<int> edgeWeights_;
-    std::vector<int> vertexWeights_;
-};

src/LanParty.cpp

@@ -27,58 +27,72 @@ const int LanParty::getPuzzleDay() const
 
 void LanParty::processDataLine(const std::string& line)
 {
-    lan_.addEdge(line.substr(0, 2), line.substr(3, 2));
+    lan_.addEdge(findOrAddVertex(line.substr(0, 2)), findOrAddVertex(line.substr(3, 2)));
 }
 
 void LanParty::finish()
 {
-    auto vertices = lan_.getVertices();
+    const auto& vertices = lan_.getLabelVertices();
-    // This works as long as "ta" is present as a computername, otherwise we would have to use vertices.find_if().
+    auto itTx = vertices.lower_bound(getFirstTxComputerName());
-    auto iterTx = vertices.find(getFirstTxComputerName());
+    const auto itTxEnd = vertices.upper_bound(getLastTxComputerName());
-    while (iterTx != vertices.end() && iterTx->second->getId() <= getLastTxComputerName())
+    while (itTx != itTxEnd)
     {
-        computeInterconnectedThreeSetCount(*iterTx->second);
+        computeInterconnectedThreeSetCount(itTx->second);
-        iterTx++;
+        itTx++;
     }
 }
 
-void LanParty::computeInterconnectedThreeSetCount(const Vertex& vertexTx)
+constexpr std::string LanParty::getFirstTxComputerName()
-{
-    auto neighborsOfTx = vertexTx.getNeighbors();
-    for (size_t i = 0; i < neighborsOfTx.size(); i++)
-    {
-        auto vertexA = neighborsOfTx[i].lock();
-        if (shallProcessVertex(*vertexA, vertexTx))
-        {
-            for (size_t j{ i + 1 }; j < neighborsOfTx.size(); j++)
-            {
-                auto vertexB = neighborsOfTx[j].lock();
-                if (shallProcessVertex(*vertexB, vertexTx))
-                {
-                    for (auto& neighborOfA : vertexA->getNeighbors())
-                    {
-                        if (vertexB == neighborOfA.lock())
-                        {
-                            part1++;
-                        }
-                    }
-                }
-            }
-        }
-    }
-}
-
-bool LanParty::shallProcessVertex(const Vertex& vertexToCheck, const Vertex& vertexTx) const
-{
-    return (vertexToCheck.getId()[0] != 't' || vertexToCheck.getId() > vertexTx.getId());
-}
-
-const std::string LanParty::getFirstTxComputerName() const
 {
     return "ta";
 }
 
-const std::string LanParty::getLastTxComputerName() const
+constexpr std::string LanParty::getLastTxComputerName()
 {
     return "tz";
 }
+
+int LanParty::findOrAddVertex(const std::string& vertexId)
+{
+    const auto& vertices = lan_.getLabelVertices();
+    const auto found = vertices.find(vertexId);
+    if (found != vertices.end())
+    {
+        return found->second;
+    }
+    else
+    {
+        return lan_.addVertex(vertexId);
+    }
+}
+
+void LanParty::computeInterconnectedThreeSetCount(const int vertexTx)
+{
+    auto itFirstNeighbor = lan_.begin(vertexTx);
+    while (itFirstNeighbor != lan_.end())
+    {
+        if (canProcessVertex(itFirstNeighbor->vertex, vertexTx))
+        {
+            auto itSecondNeighbor = itFirstNeighbor;
+            itSecondNeighbor++;
+            while (itSecondNeighbor != lan_.end())
+            {
+                if (canProcessVertex(itSecondNeighbor->vertex, vertexTx))
+                {
+                    if (lan_.areAdjacent(itFirstNeighbor->vertex, itSecondNeighbor->vertex))
+                    {
+                        part1++;
+                    }
+                }
+                itSecondNeighbor++;
+            }
+        }
+        itFirstNeighbor++;
+    }
+}
+
+bool LanParty::canProcessVertex(const int vertexToCheck, const int vertexTx) const
+{
+    const std::string& label{ lan_.getVertexLabel(vertexToCheck) };
+    return (label[0] != 't' || label > lan_.getVertexLabel(vertexTx));
+}

src/RamRun.cpp

@@ -65,7 +65,7 @@ void RamRun::processDataLine(const std::string& line)
                 auto graph = buildGraph();
                 dijkstraResult_ = graph.dijkstra(vertexReferences_[0][0]);
                 if (dijkstraResult_.distances[vertexReferences_[memorySize_ - 1][memorySize_ - 1]]
-                    == WeightedEdgeGraph::getInfiniteDistance())
+                    == WeightGraph::getInfiniteDistance())
                 {
                     // Path is blocked.
                     part2 = line;
@@ -105,9 +105,9 @@ bool RamRun::tryMarkCorrupted(const std::string& line, int& corruptedVertex)
     return false;
 }
 
-WeightedEdgeGraph RamRun::buildGraph()
+WeightGraph RamRun::buildGraph()
 {
-    WeightedEdgeGraph graph;
+    WeightGraph graph;
     for (size_t j = 0; j < vertexReferences_.getNRows(); j++)
     {
         for (size_t i = 0; i < vertexReferences_.getNColumns(); i++)
@@ -132,15 +132,14 @@ WeightedEdgeGraph RamRun::buildGraph()
             }
         }
     }
-
     return graph;
 }
 
-int RamRun::getVertex(WeightedEdgeGraph& graph, const size_t x, const size_t y)
+int RamRun::getVertex(WeightGraph& graph, const size_t x, const size_t y)
 {
     if (vertexReferences_[y][x] == getUnknownVertexReference())
     {
-        vertexReferences_[y][x] = graph.addVertex();
+        vertexReferences_[y][x] = graph.addVertex(0);
     }
     return vertexReferences_[y][x];
 }

src/ReindeerMaze.cpp

@@ -40,7 +40,7 @@ void ReindeerMaze::finish()
     // do not want to hardcode this.
     VertexAttachedPositions vertexAttachedPositions;
 
-    WeightedEdgeGraph graph{};
+    WeightGraph graph{};
     auto entry = graph.addVertex(0);
     auto exit = graph.addVertex(0);
     buildPathSegmentGraph(graph, vertexAttachedPositions, entry, exit);
@@ -72,7 +72,7 @@ constexpr int ReindeerMaze::getTurnCost()
 
 // Constructs the graph of path segment incidences, starting with a graph that already contains the entry and the exit
 // vertices.
-void ReindeerMaze::buildPathSegmentGraph(WeightedEdgeGraph& graph, VertexAttachedPositions& vertexAttachedPositions,
+void ReindeerMaze::buildPathSegmentGraph(WeightGraph& graph, VertexAttachedPositions& vertexAttachedPositions,
     const int entry, const int exit)
 {
     // Uses list for work items to prevent invalidation of iterators on add.
@@ -243,7 +243,7 @@ void ReindeerMaze::addCheckedIncidence(std::vector<ReindeerMazePathIncidence>& i
     }
 }
 
-void ReindeerMaze::addPathSegmentEdges(WeightedEdgeGraph& graph, const ReindeerMazePathIncidence& pathIncidence,
+void ReindeerMaze::addPathSegmentEdges(WeightGraph& graph, const ReindeerMazePathIncidence& pathIncidence,
     const std::vector<ReindeerMazePathIncidence>& otherPathIncidences)
 {
     for (auto& otherIncidence : otherPathIncidences)
@@ -267,13 +267,13 @@ std::pair<int, int> ReindeerMaze::makePositionsIdPair(const Point2& position1, c
     return std::make_pair(position1.x * offset + position1.y, position2.x * offset + position2.y);
 }
 
-int ReindeerMaze::calcShortestPaths(const WeightedEdgeGraph& graph,
+int ReindeerMaze::calcShortestPaths(const WeightGraph& graph,
     const VertexAttachedPositions& vertexAttachedPositions, const int entry, const int exit,
     const std::vector<int>& shortestDistances)
 {
     std::set<int> shortestPathsVertices{};
 
-    std::stack<WeightedEdgeGraph::NeighborIterator> stack{};
+    std::stack<Graph::NeighborIterator> stack{};
     auto v = graph.begin(entry);
     stack.emplace(v);
     int cost{ 0 };

src/common/Graph.cpp

@@ -1,5 +1,5 @@
 // Solutions to the Advent Of Code 2024.
-// Copyright (C) 2024  Stefan Müller
+// Copyright (C) 2025  Stefan Müller
 //
 // This program is free software: you can redistribute it and/or modify it under
 // the terms of the GNU General Public License as published by the Free Software
@@ -15,32 +15,53 @@
 
 #include <aoc/common/Graph.hpp>
 
-#include <memory>
+int Graph::addVertex()
-
-const std::map<std::string, std::shared_ptr<Vertex>>& Graph::getVertices() const
 {
-    return vertices_;
+    firstVertexIncidences_.push_back(-1);
+    return static_cast<int>(firstVertexIncidences_.size()) - 1;
 }
 
-void Graph::addEdge(const std::string& vertexId1, const std::string& vertexId2)
+void Graph::addEdge(const int vertex1, const int vertex2)
 {
-    auto v1 = findOrAddVertex(vertexId1);
+    incidenceVertices_.push_back(vertex2);
-    auto v2 = findOrAddVertex(vertexId2);
+    nextIncidences_.push_back(firstVertexIncidences_[vertex1]);
-    v1->addNeighbor(v2);
+    firstVertexIncidences_[vertex1] = static_cast<int>(incidenceVertices_.size()) - 1;
-    v2->addNeighbor(v1);
+
+    incidenceVertices_.push_back(vertex1);
+    nextIncidences_.push_back(firstVertexIncidences_[vertex2]);
+    firstVertexIncidences_[vertex2] = static_cast<int>(incidenceVertices_.size()) - 1;
 }
 
-std::shared_ptr<Vertex> Graph::findOrAddVertex(const std::string& vertexId)
+size_t Graph::getNVertices() const
 {
-    auto iter = vertices_.find(vertexId);
+    return firstVertexIncidences_.size();
-    if (iter != vertices_.end())
+}
+
+size_t Graph::getNEdges() const
+{
+    return nextIncidences_.size() >> 1;
+}
+
+bool Graph::areAdjacent(const int vertex1, const int vertex2) const
+{
+    auto it = begin(vertex1);
+    while (it != end())
     {
-        return (*iter).second;
+        if (it->vertex == vertex2)
-    }
+        {
-    else
+            return true;
-    {
+        }
-        auto v = std::make_shared<Vertex>(vertexId);
+        it++;
-        vertices_.insert({ vertexId, v });
-        return v;
     }
+    return false;
+}
+
+Graph::NeighborIterator Graph::begin(const int vertex) const
+{
+    return { *this, vertex };
+}
+
+Graph::NeighborIterator Graph::end() const
+{
+    return { *this, -1 };
 }

src/common/LabelGraph.cpp

@@ -0,0 +1,53 @@
+// Solutions to the Advent Of Code 2024.
+// Copyright (C) 2025  Stefan Müller
+//
+// This program is free software: you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include <aoc/common/LabelGraph.hpp>
+
+int LabelGraph::addVertex(const std::string& label)
+{
+    vertexLabels_.push_back(label);
+    labelVertices_.insert({ label, static_cast<int>(vertexLabels_.size()) - 1 });
+    return graph_.addVertex();
+}
+
+void LabelGraph::addEdge(const int vertex1, const int vertex2)
+{
+    graph_.addEdge(vertex1, vertex2);
+}
+
+bool LabelGraph::areAdjacent(const int vertex1, const int vertex2) const
+{
+    return graph_.areAdjacent(vertex1, vertex2);
+}
+
+const std::string& LabelGraph::getVertexLabel(const int vertex) const
+{
+    return vertexLabels_[vertex];
+}
+
+const std::map<std::string, int>& LabelGraph::getLabelVertices() const
+{
+    return labelVertices_;
+}
+
+Graph::NeighborIterator LabelGraph::begin(const int vertex) const
+{
+    return graph_.begin(vertex);
+}
+
+Graph::NeighborIterator LabelGraph::end() const
+{
+    return graph_.end();
+}

src/common/WeightGraph.cpp

@@ -13,45 +13,41 @@
 // You should have received a copy of the GNU General Public License along with
 // this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#include <aoc/common/WeightedEdgeGraph.hpp>
+#include <aoc/common/WeightGraph.hpp>
 
 #include <limits>
 #include <queue>
 
-WeightedEdgeGraph::WeightedEdgeGraph()
+constexpr int WeightGraph::getInfiniteDistance()
-    : firstVertexIncidences_{}, vertexEdgeIncidences_{}, edgeWeights_{}
 {
+    return std::numeric_limits<int>::max();
 }
 
-int WeightedEdgeGraph::addVertex(const int weight)
+int WeightGraph::addVertex(const int weight)
 {
-    firstVertexIncidences_.push_back(-1);
     vertexWeights_.push_back(weight);
-    return (int)firstVertexIncidences_.size() - 1;
+    return graph_.addVertex();
 }
 
-void WeightedEdgeGraph::addEdge(const int vertex1, const int vertex2, const int weight)
+void WeightGraph::addEdge(const int vertex1, const int vertex2, const int weight)
 {
-    vertexEdgeIncidences_.emplace_back(vertex2, firstVertexIncidences_[vertex1]);
-    firstVertexIncidences_[vertex1] = (int)vertexEdgeIncidences_.size() - 1;
-    vertexEdgeIncidences_.emplace_back(vertex1, firstVertexIncidences_[vertex2]);
-    firstVertexIncidences_[vertex2] = (int)vertexEdgeIncidences_.size() - 1;
     edgeWeights_.push_back(weight);
+    graph_.addEdge(vertex1, vertex2);
 }
 
-int WeightedEdgeGraph::getVertexWeight(const int vertex) const
+int WeightGraph::getVertexWeight(const int vertex) const
 {
     return vertexWeights_[vertex];
 }
 
-int WeightedEdgeGraph::getEdgeWeight(const int edge) const
+int WeightGraph::getEdgeWeight(const int edge) const
 {
     return edgeWeights_[edge];
 }
 
-WeightedEdgeGraph::PathsResult WeightedEdgeGraph::dijkstra(const int source) const
+GraphPathsResult WeightGraph::dijkstra(const int source) const
 {
-    PathsResult result(firstVertexIncidences_.size(), getInfiniteDistance(), -1);
+    GraphPathsResult result(graph_.getNVertices(), getInfiniteDistance(), -1);
     auto compare = [&result](int left, int right) { return result.distances[left] > result.distances[right]; };
     std::priority_queue<int, std::vector<int>, decltype(compare)> queue{ compare };
 
@@ -78,17 +74,12 @@ WeightedEdgeGraph::PathsResult WeightedEdgeGraph::dijkstra(const int source) con
     return result;
 }
 
-constexpr int WeightedEdgeGraph::getInfiniteDistance()
+Graph::NeighborIterator WeightGraph::begin(const int vertex) const
 {
-    return std::numeric_limits<int>::max();
+    return graph_.begin(vertex);
 }
 
-WeightedEdgeGraph::NeighborIterator WeightedEdgeGraph::begin(const int vertex) const
+Graph::NeighborIterator WeightGraph::end() const
 {
-    return { *this, vertex };
+    return graph_.end();
-}
-
-WeightedEdgeGraph::NeighborIterator WeightedEdgeGraph::end() const
-{
-    return { *this, -1 };
 }